Born Agnes Keay in 1882, she attended Forest Lodge during the early 1890s before moving to Western Australia in 1895. In 1912, she sadly lost her husband to tuberculosis and became a teacher to support her three young children. During the 1920s she became involved in community activities, which sparked her political awareness. With her commanding presence, renowned eloquence, great, she proved to be a formidable committee woman. In the wider community she grew increasingly pro-active in numerous social issues – particularly those benefiting women, children, the disabled and the aged—and held high office in the Liberal and Country League of WA. After retiring from teaching in 1941, Agnes served as part-time secretary of the Presbyterian Children's Homes and, a few years later, became Western Australia's first Presbyterian woman lay preacher. In 1947 she accepted a place on the Liberal and Country League's ticket for the Senate, taking her seat in 1950. She retired in 1962. Agnes Robertson recalled late in her life that she still had her "copy of the Blue Certificate signed from Forest Lodge School stating that at 13 years and 11 months of age I was sufficiently educated to venture out into the world." This short education certainly launched a long and remarkable career.